Q.Antibiotics are mainly obtained from
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Microbes as a Source of Medicines
Beyond antibiotics, several microbes are cultured specifically to harvest a single bioactive molecule that becomes a life-saving drug — the organism itself is never the product, its metabolite is.
The Two NCERT Examples
- Cyclosporin-A — an immunosuppressive agent, produced by the fungus Trichoderma polysporum. It is given to organ-transplant patients to suppress the recipient's immune system just enough to prevent it from rejecting the transplanted organ as "foreign," without leaving the patient defenceless against infection.
- Statins — blood-cholesterol-lowering agents, produced by the yeast Monascus purpureus. Statins work by competitively inhibiting the enzyme HMG-CoA reductase, which the body needs to synthesise cholesterol; lowering this enzyme's activity lowers blood cholesterol.
Why This Matters …
Antibiotics are substances made by micro-organisms that kill or check other microbes, and most clinically used ones come from soil actinomycetes such as Streptomyces. Among the options, therefore, bacteria are the main source. …
Bacteria (especially actinomycetes such as Streptomyces) are the chief source of antibiotics among the given choices.
Concept. Antibiotics are chemical substances produced by some micro-organisms that can kill or inhibit other micro-organisms.
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Showing the 12 most recent of 17 on this concept.
- CBSE 2026Set A1 markMCQQ.Which of the following is the blood cholesterol lowering agent?(a) Statin(b) Cyclosporin-A(c) Antibiotic(d) Streptokinase
›Reveal solutionSolution
Statins are the blood-cholesterol-lowering agents; the correct option is (a).
Statins are produced by the yeast Monascus purpureus and are used as blood-cholesterol-lowering agents. They act by competitively inhibiting the enzyme (HMG-CoA reductase) responsible for cholesterol synthesis in the body.
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- CBSE 2026Set A1 markMCQQ.Which of the following pairs is incorrect?(a) Cyclosporin-A – Produced by fungus(b) Statin – Produced by yeast(c) Streptokinase – Produced by bacteria(d) Butyric acid – Produced by fungus
›Reveal solutionSolution
The incorrect pair is butyric acid–fungus; the correct option is (d).
Checking each pair:
- (a) Cyclosporin-A – produced by the fungus Trichoderma polysporum. Correct.
- (b) Statin – produced by the yeast Monascus purpureus. Correct.
- (c) Streptokinase – produced by the bacterium Streptococcus. Correct. …
- CBSE 2025Set F1 markMCQQ.Which of the following is used to reduce the amount of cholesterol in the blood?(a) Statin(b) Cyclosporin(c) Lipase(d) Streptokinase
›Reveal solutionSolution
Statins are the cholesterol-lowering agents.
Statins, produced commercially by the yeast Monascus purpureus, are used as blood-cholesterol-lowering agents. They act by competitively inhibiting HMG-CoA reductase, the enzyme responsible for cholesterol synthesis in the body. Cyclosporin A (from Trichoderma polysporum) is an immunosuppressa …
- CBSE 2025Set A1 markQ.Fill in the blank with the correct answer: Cyclosporin-A is produced by the fungus ______.
›Reveal solutionSolution
Cyclosporin-A comes from the fungus Trichoderma polysporum.
Cyclosporin-A is a widely used immunosuppressive drug administered to patients undergoing organ transplantation to prevent immune rejection of the transplanted organ. It is a fungal metabolite produced by Trichoderma polysporum, obtained through microbial fermentation. This is one of the classic examples in the NCERT syllabus of a …
- CBSE 2025Set ANNUAL1 markQ.Fill in the blank: Statins produced by the yeast Monascus Purpureus have been commercialised as ___ lowering agents.
›Reveal solutionSolution
Statins produced by the yeast Monascus purpureus are marketed as blood-cholesterol-lowering drugs.
Statins are compounds that competitively inhibit the enzyme HMG-CoA reductase, a key enzyme in the body's cholesterol biosynthesis pathway. Statins extracted/produced from the yeast Monascus purpureus have been commercially developed and …
- CBSE 2025Set ANNUAL1 markQ.Write the name of the fungus used in production of cyclosporin A.
›Reveal solutionSolution
The immunosuppressive drug cyclosporin A, used in organ-transplant patients, is produced by the fungus Trichoderma polysporum.
Cyclosporin A is widely used clinically as an immunosuppressive agent to prevent rejection of transplanted organs. It is a bioactive compound produced by the fungus Trichoderma polysporum …
- CBSE 2025Set ANNUAL1 markMCQQ.Statins are produced by(a) Trichoderma polysporum(b) Monascus Purpureus(c) Streptococcus(d) Penicillium notatum
›Reveal solutionSolution
Statins, which lower blood cholesterol by inhibiting the enzyme HMG-CoA reductase, are commercially produced using the yeast Monascus purpureus.
Monascus purpureus is fermented to produce statins, a class of drugs used to manage high blood cholesterol. Statins act by competitively inhibiting HMG-CoA reductase, the rate-limiting enzyme in the body's cholesterol biosynthesis pathway, thereby lowering serum cholesterol levels. (This is distinct from …
- CBSE 2025Set ANNUAL1 markQ.Antibiotics are chemical substances produced by some microbes that can kill or inhibit disease-causing microbes.
›Reveal solutionSolution
By definition, antibiotics are compounds produced by certain microorganisms (moulds/bacteria) that can kill or stop the growth of other, usually disease-causing, microorganisms.
Antibiotics are chemical substances, produced by some microbes (such as the fungus Penicillium notatum, from which Alexander Fleming accidentally discovered penicillin in 1929), which can kill or retard the growth of other disease-causing microbes. They function by interfering with essential processes in the target microbe, such as cell wall synthesis, p …
- CBSE 2025Set ANNUAL1 markMCQQ.A compound which is produced by an organism that can kill or retard the growth of other organism is called(a) xenobiotic(b) antibiotic(c) antibody(d) probiotic
›Reveal solutionSolution
An antibiotic is a microbially-produced compound that kills or inhibits the growth of other (typically disease-causing) microorganisms.
An antibiotic is defined as a chemical substance, produced (wholly or partly) by a microorganism, which can kill, or inhibit the growth of, other disease-causing microorganisms — while (ideally) having minimal or no harmful effects on the host. The first antibiotic discovered was penicillin, by Alexander Fleming, from the fungus Penicillium notatum. Antibodies are immune proteins produced by the body itself in response to an antigen (not produced by microbes to affect other organisms); a xenobiotic is …
- CBSE 2024Set ANNUAL1 markMCQQ.Antibiotics are produced by :(a) By Vitamins(b) By Chemical(c) By Nematod(d) By Microbes
›Reveal solutionSolution
Antibiotics are chemical substances produced by microbes that kill or inhibit other microbes.
Antibiotics such as penicillin (from the fungus Penicillium notatum) and streptomycin (from the bacterium Streptomyces) are metabolites produced by microorganisms (bacte …
- CBSE 2024Set E1 markMCQQ.Which of the following inhibits synthesis of cholesterol?(a) Protease(b) Streptokinase(c) Penicillin(d) Statin
›Reveal solutionSolution
Statins lower blood cholesterol by inhibiting its synthesis.
Statins are produced by the yeast Monascus purpureus and are used as blood-cholesterol lowering agents. They act by competitively inhibiting the enzyme (HMG-CoA reductase) responsible for the synthesis of cholesterol in the body, thereby reducing cholesterol levels.
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- CBSE 2023Set ANNUAL1 markMCQQ.Antibiotics are produced by -(a) Vitamins(b) Protozoans(c) Microbes(d) Chemicals
›Reveal solutionSolution
Antibiotics are chemical substances produced naturally by microorganisms.
Antibiotics are substances produced by certain living microorganisms (bacteria and fungi) that can kill, or inhibit the growth of, other disease-causing microorganisms. For example, Penicillin is obtained from the fungus Penicillium notatum and Streptomycin …
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